By Patricia Jones Yellowstone National Park’s 2024 bison management plan is facing lawsuits from opposing sides of the bison debate. Montana officials argue that the plan allows too many bison and does not sufficiently protect livestock interests. Conservation organisations argue that it continues unnecessary capture, slaughter and disease-control practices based on outdated assumptions.
The two principal lawsuits have been consolidated for scheduling purposes in the U.S. District Court for the District of Montana. As of July 31, 2026, neither case has produced a final ruling on whether the 2024 plan is lawful.
What Is the Yellowstone Bison Management Plan?
The National Park Service approved the new bison management plan in July 2024 after completing an environmental impact statement under the National Environmental Policy Act, commonly called NEPA.
The plan replaced much of the management approach established under the 2000 Interagency Bison Management Plan. Its objectives include maintaining a sustainable wild bison population, reducing conflicts outside Yellowstone, addressing the possible transmission of brucellosis, protecting people and property and fulfilling federal responsibilities toward Tribal Nations.
Under the 2024 decision, Yellowstone generally manages the herd within a post-calving population range of approximately 3,500 to 6,000 bison, with a long-term average of about 5,000 animals. Management tools include Tribal and state hunting outside the park, transfers of disease-free bison to Tribal lands and transfers of meat and hides to Tribes.
The National Park Service says the updated plan reflects changing conditions, including fewer cattle near the park, newer brucellosis information, expanded Tribal hunting and increased opportunities to transfer Yellowstone bison to Tribal conservation herds.
Montana’s Lawsuit Against the Plan
On December 31, 2024, the State of Montana, Governor Greg Gianforte, the Montana Department of Livestock and Montana Fish, Wildlife and Parks filed a federal lawsuit challenging the plan.
The case was originally captioned State of Montana v. Haaland. Following changes in federal officeholders, the litigation has also been identified as State of Montana v. Burgum.
Montana alleges that the National Park Service failed to cooperate meaningfully with state officials while developing the plan. The state also argues that the environmental review did not adequately examine the effects of a larger bison population migrating into Montana.
The state’s concerns include:
- Possible exposure of cattle to brucellosis
- Property damage caused by migrating bison
- Public-safety concerns
- The cost of managing bison after they leave federal land
- The effect of the plan on Montana’s livestock industry
- Whether the federal government adequately considered stricter population controls
- Whether state scientific and technical comments were properly evaluated
Montana seeks to have the 2024 Record of Decision vacated. Vacating the decision could remove the legal approval for the new plan and require the National Park Service to reconsider its management approach.
The allegations have not been proven. The National Park Service and organisations defending the plan dispute Montana’s description of the planning process and the scientific risks.
Conservation Groups’ Lawsuit
A separate lawsuit was filed by the Alliance for the Wild Rockies and the Council on Wildlife and Fish.
The case, identified as Alliance for the Wild Rockies v. Carlstrom and previously as Alliance for the Wild Rockies v. Hammond, challenges the same 2024 plan but approaches the issue from the opposite direction.
The conservation plaintiffs argue that the National Park Service continues to manage wild bison mainly as a disease threat to cattle rather than as native wildlife. They claim that the environmental impact statement failed to use the best available science concerning brucellosis, migration and the effectiveness of population-control measures.
Their concerns include:
- Capture and removal of bison from the wild
- Transfer of bison for slaughter
- Continued reliance on the 2000 management framework
- Whether population reductions have meaningfully lowered brucellosis prevalence
- The limited presence of cattle in some areas used by migrating bison
- Failure to evaluate alternatives allowing more bison to occupy suitable habitat
- Whether the plan gives excessive weight to livestock concerns
Unlike Montana, the conservation plaintiffs have sought remand without automatically vacating the plan. That approach could allow parts of the 2024 system to remain in operation while the National Park Service corrects its environmental analysis.
Why Were the Two Lawsuits Consolidated?
In September 2025, U.S. District Judge Brian Morris consolidated the Montana and Alliance cases for scheduling purposes.
The cases remain legally distinct, but both challenge the sufficiency of the same 2024 bison plan and its NEPA analysis. The court concluded that placing them on parallel schedules would reduce the risk of inconsistent rulings and unnecessary duplication.
The consolidation order specifically recognised the unusual situation: Montana wants the plan vacated because it allegedly provides inadequate control of bison, while the conservation plaintiffs challenge the plan for continuing restrictive management practices.
Tribes and Conservation Groups Enter the Case
The Fort Peck Assiniboine and Sioux Tribes, together with several conservation organisations, sought permission to participate in the litigation in defence of the 2024 plan.
The organisations include the National Parks Conservation Association, Defenders of Wildlife, the Greater Yellowstone Coalition and the Park County Environmental Council.
These parties argue that invalidating the plan could interfere with the Bison Conservation Transfer Program. The programme places Yellowstone bison that have completed brucellosis testing on Tribal lands for conservation and cultural restoration.
They also maintain that Yellowstone bison have deep cultural, spiritual and nutritional importance for Tribal Nations and that Tribal interests cannot be represented fully by either Montana or the federal government.
According to the groups seeking to defend the plan, more than 400 Yellowstone bison had been transferred to 26 Tribes through the conservation programme by February 2025.
The Brucellosis Dispute
Brucellosis is a bacterial disease that can cause reproductive problems in cattle, elk and bison. The possibility of transmission to livestock has shaped Yellowstone bison policy for decades.
Montana argues that allowing more bison to migrate outside Yellowstone could increase the risk to cattle and create additional disease-control expenses.
Conservation groups respond that there has been no documented case of Yellowstone bison transmitting brucellosis directly to cattle. They also argue that elk present a recognised transmission risk but are not subjected to the same restrictive management system.
The absence of a documented bison-to-cattle transmission does not prove that transmission is biologically impossible. The legal dispute concerns whether the National Park Service properly evaluated the actual level of risk and explained why its chosen controls remain necessary.
National Park Service Begins a Supplemental Review
On April 29, 2026, the National Park Service announced that it would prepare a Supplemental Environmental Impact Statement, or SEIS, for the 2024 plan.
The agency said that seasonal bison migration had become less predictable in its timing and duration. According to the National Park Service, this change affected assumptions used in the 2024 environmental analysis.
The supplemental review may develop new management alternatives, reconsider options previously dismissed and examine issues raised in both federal lawsuits. The initial public-comment period closed on May 29, 2026, and another comment opportunity is expected when a draft supplemental statement is released.
Beginning the SEIS does not mean that the National Park Service has admitted that the original plan was unlawful. Federal agencies sometimes conduct supplemental reviews when circumstances change or when additional analysis may reduce legal uncertainty.
Judge Refuses to Pause the Lawsuits
The federal government asked the court to pause the consolidated cases while the National Park Service completed its supplemental environmental review.
On July 21, 2026, Judge Brian Morris denied that request. The ruling allows the challenges to continue while the SEIS process proceeds separately.
The court was not persuaded that an indefinite stay was justified, particularly because the agency had not committed to resolving every issue raised by the conservation plaintiffs. The decision did not determine whether the bison plan violates NEPA or any other law. It concerned only whether the litigation should be suspended.
The Earlier Neighbors Against Bison Slaughter Case
The current litigation follows an earlier case filed by Neighbors Against Bison Slaughter and a local resident.
That lawsuit challenged bison hunting near Beattie Gulch, an area outside Yellowstone in the Custer Gallatin National Forest. The plaintiffs alleged that concentrated hunting affected wildlife, the environment and the safety of nearby residents.
The case contributed to court oversight that required the National Park Service to conduct additional NEPA analysis. The court closed the case after the agency issued the 2024 environmental impact statement and Record of Decision.
The plaintiffs later attempted to reopen it. On March 13, 2026, Judge Morris denied the request, concluding that the conditions for reopening the old proceeding had not been established. The ruling did not prevent separate lawsuits challenging the legality of the completed 2024 plan.
Has the 2024 Bison Plan Been Cancelled?
No. The 2024 Yellowstone bison management plan has not been cancelled or declared unlawful.
The plan remains the National Park Service’s operative management framework while litigation and supplemental environmental review continue. A future court order or a new agency decision following the SEIS could modify, replace or vacate all or part of it.
What Could Happen Next?
The court may eventually:
- Uphold the 2024 plan
- Find that the environmental review was inadequate
- Return the plan to the National Park Service for additional analysis
- Vacate the Record of Decision
- Allow the plan to remain temporarily during remand
- Resolve the Montana and conservation claims differently
- Dismiss claims that have become moot after the supplemental review
The National Park Service could also issue a revised plan before the court reaches a final decision. Whether that would end the lawsuits would depend on how completely the revised action addresses the challenged issues.
Current Legal Status
As of July 31, 2026, two principal lawsuits challenging the Yellowstone bison management plan remain active and are proceeding on coordinated schedules.
Montana argues that the plan provides insufficient protection for livestock, property and state interests. Conservation plaintiffs argue that it imposes excessive controls on wild bison and relies on outdated disease-management assumptions.
Meanwhile, Tribal and conservation intervenors are defending portions of the plan that support Tribal hunting, food transfers and the restoration of disease-free Yellowstone bison to Tribal lands.
No settlement fund or personal compensation programme is involved. These are environmental and administrative-law cases seeking changes to government policy rather than payments to individual bison advocates, ranchers or Yellowstone visitors.